I Made A $30 Tracker, Is It Any Good?

i just built this star tracker for about thirty  dollars. It's a very simple mechanism instead   of using a motorized gear to track the stars  like in a commercial star tracker this tracker   makes me the motor and i manually track the sky  by turning this threaded bolt and this counteracts   the earth's rotation stick around and i'll explain  how it works show you how to build one and then   we will do a real world test of it by shooting  several two-minute exposures of the milky way and   the Rho Ophiuchi Cloud Complex which is beautiful  with a basic DSLR and a 24 millimeter lens hello there my name is Nico Carver and my youtube  channel nebula photos is all about helping people   learn astrophotography i'm especially interested  in how to approach astrophotography on a budget   of course many aspects of astrophotography  become easier if you just throw money at them   and it's easy to go down a gear buying rabbit hole  i've been guilty of it myself but i also enjoy   getting the most out of budget gear and budget  techniques which is what i'm going to be showing   you tonight with this i do have a patreon to  support this channel and if you join the patreon   you can also join my discord server which is a  great place to ask questions and talk to others in   the nebula photos community including me i'm going  to say up front here i'm not super skilled in diy   stuff but when i read about this star tracker  that's basically just two boards connected by a   hinge with a ball head on top and then a threaded  bolt that you turn uh to track i thought well   this sounds simple enough that even i should be  able to make one and and i did and it works and   the inventor of this style tracker is  george haig who released the idea for free   and described how to make it in this april  1975 issue of sky and telescope magazine   it's called sometimes called a scotch  mount because george haig is scottish   and probably the most common name for it though  is a barn door tracker and it's been a popular   diy project for amateur astronomers ever since he  published this in 1975 and there have been many   different versions of the design improvements  to it maybe but i'm going to make the original   hague design both to keep the cost low and  because i'm fascinated by the simplicity of it before we jump into making one let me just very  quickly explain how this kind of tracker works   and it's pretty easy in terms of the math so  this isn't going to take too long the reason the   stars move from our vantage point is of course  because the earth is rotating around its axis   and the earth moves 360 degrees or one full  rotation every 24 hours for the astrophotographer   what this means is that if you just point your  camera at the night sky and leave the shutter open   for a long time the stars will trail meaning  turn from little points to arced lines that   we call star trails this of course also blurs  out any deep sky object like a nebula or galaxy   and one way to get around this which i've  described in several other videos now   is just to take very short exposures and then  stacking many hundreds or thousands of these short   exposures together with stacking software the name  for this that's sort of catching on is untracked   astrophotography an untracked astro works  well but it just has some definite limitations   the main one being that you have to take  hundreds and hundreds of photos and so that can   wear out your mechanical shutter in the dslr  and then it also just takes a long time to   you know transfer all the files and  stack them all together on your computer   and another limitation is that it works really  well for bright deep sky objects like orion   and andromeda but not so well for dim ones so to  solve this we usually turn to star trackers which   just move at a constant rate that's opposite  the the earth's rotation in the opposite   direction and that lets us take much longer  exposures with the camera with pinpoint stars   so as i said earlier earth is rotating 360  degrees every 24 hours we can divide that   down to 15 degrees per hour or 0.25 degrees per  minute so if we look at these two boards what we   really need to do is move one away from the other  at a rate of 0.25 degrees per minute and that will   keep up with the stars now a very common piece  of hardware that you can buy is a quarter inch   20 bolt meaning it's quarter inch in diameter and  it has a thread spacing of 20 threads per inch   and so that's we're going to use to drive  our mounts we're gonna because we can   drive that at one revolution per minute it'll  travel one inch every 20 minutes or 0.05   inches per one minute so we know now okay we  have to move 0.05 inches per minute and we   want the boards to move apart from each other at  0.25 degrees so all we need now is to solve this   equation and if you remember some trigonometry you  might already know what's coming here what we do   is we use a simple formula and what we need is  the hypotenuse and the hypotenuse is going to   equal the opposite side of the angle so we know  that's 0.05 we know the angle is 0.25 so we can do   is divide by sine times the angle so 0.05 divided  by sine times 0.25 and we get 11.4 inches or 290   millimeters for those metric folks and so we want  the hole for the bolt to be 290 millimeters away   from the hinge and then if we uh track at one  rotation per minute we're gonna get perfect stars   and yes for this to work we also need to be polar  aligned and so that's the hard part keeping this   build on the cheap and so what i did is i'm  just using a metal drinking straw on here taped   right by the hinge to site polaris but really  this is the first thing that i want to improve   in my next revision of this mount as the straw  to cite polaris is really a bit of a pain to use   it's not that accurate um and it  won't work for the southern hemisphere   so i'm on the lookout for for a used finder scope  i mean a used polar scope would be even better   but something a laser i don't know but um let  me know in the comments if you have any kinds   of ideas for an accurate way to polar align this  kind of mount a diy mount as cheaply as possible   okay anyways now that we know how it works let's  go through the steps of building it and i made   a pdf guide you can download from the link in  the description for building it i'm going to go   through the steps fairly quickly so the guide will  be a helpful reference if you if you want to look   at that while you're building one yourself step 1  measure and cut two pieces of 1 by 6 lumber to 12   and 11 16 inches long that's 322 millimeters  for the metric folks if you don't have a saw   home depot or other kind of home improvement  hardware stores might uh cut the lumber for   you in the store step two put your hinge or  hinges if you're using two along the edges   of the boards to mark out where the holes  are going to go and then drill some small   holes to attach the hinges and then you're going  to screw on the hinge with some small wood screws   i'll just note here i was able to find a six inch  long hinge and i'll put a link in the description   of of one online that i found if you can't find  that though two smaller hinges like two three inch   hinges would work just as well it should now look  like this with two boards connected by the hinge   step three now you want to measure out a  spot on the bottom board exactly 11.42 inches   or 290 millimeters from the hinge and make it  centered uh in terms of top to bottom on the board   and mark this and then drill  a quarter inch hole there   you're then going to glue and hammer in a quarter  inch t-nut into the top of the bottom board   and when you glue it or epoxy it be careful not to  get any of the glue into the threads of the t-nut   it's just to secure the t-nut to the board  a little bit better than you could by just   hammering it step four repeat step three except  this time put the t-nut in the exact middle of   your bottom board so that that would be six and  five-sixteenths of an inch or 161 millimeters   this is where you will attach the tracker to your  tripod step five um i've lost the sunlight so   i'm indoors now this is how your tracker should  look and you can go ahead and screw in the long   quarter inch 20 carriage bolt with the round head  into the t-nut that is 290 millimeters away from   the hinge this is going to be your drive bolt for  the tracker and you can test it out if you want step six print out the pattern i'm providing to  make your clock wheel you can just print it out   on regular printer paper and glue it onto a cd  but if you happen to have avery cd labels like   i did laying around you can use those makes it  even easier step seven we're now going to secure   the clock wheel and a handle which is i'm just  using a sort of a little metal brace here i found   to the bottom of the drive bolt and i'd recommend  using some nuts washers and epoxy and then   tighten it all up with some pliers so that it's  all secured very well to the bottom of the bolt   and very permanent and once you have all that  done you should be able to easily turn the bolt   up and down with the handle like this and the  clock wheel will rotate around now go ahead and   decide where to attach your ball head to the top  board and drill a hole so you can attach it with   a shorter quarter inch 20 bolt i put my ball head  in the center uh lengthwise but towards the top   widthwise um i'm putting it towards the top of  what will be the north end of the board because   i'm going to be mostly using my tracker for  milky way which will always be to the south   here so i was thinking for balance with lenses  that the weight would be more distributed equally   this way if the lens is coming out uh towards  the south i'm not sure if this really makes any   difference but that was the the thought behind it  step nine measure the center point of your boards   at the end of it where the clock wheel is and  drill out two little holes for the screw eyes   and you can screw those in by hand and then  you can attach a rubber band around these to   give a little tension to the system and turn the  screw eyes this way so you can look down and see   your how your clock wheel is pointed  right through the center of those   and step 10 attach your polar alignment device  and align it with the hinge of the tracker as i   said earlier the drinking straw works okay  for very wide angle lenses like i'm using   i'm going to be doing 24 millimeters but to  use this at 50 or 70 millimeters i think i'd   need to find a better polar alignment  device and that's it let's go test it okay it's 3 20 am i'm in a portal 4 this will  be my first milky way of the season i'm really   excited i'm ready to actually try this thing out  and the first step is we need to pull or align it   and i'm just going to try to cite polaris with  this metal drinking straw just try to center it   in the straw polaris of course is the the last  star in the little handle of the little dipper   um and this is just going to be a good enough  polar alignment not a great polar alignment but   since polaris is actually about a half a  degree off from the pole um but hopefully   for a wide angle lens like this 24 millimeter  this will work well enough so here we go   all right the second step now that polar  aligned is we have to find our target   um by moving the camera around on the  ball head until we're pointing at it so   i want to be pointing at the row of yuki  area which is pretty easy to find because   there's a bright visible redistart called antares  which is right in the middle and it's part of   again the easy to spot scorpius constellation  so here we go i'm just gonna go find it the third step now is i want to focus on  the stars using the live view i'll just   zoom in to 10 times and try to make the  stars as small as possible on the screen the fourth step is i'm going to put the camera  into bulb mode and just connect this simple bulb   timer or shutter release um so i can take two  minute long exposures this has a little lock   so i'll basically just start an exposure  lock it and then at the end of two minutes   unlock it so now we're all ready to start tracking   let's see how it goes okay my first few tests  were not successful i was still getting sort of   trailed stars i found through a lot of trial and  error though that with this camera and lens i'm   using here which again are the rebel t7 or 1500d  and the rokinon 24 millimeter lens at 2.8 that i   need to move the clock wheel or the the bolt at  a rate of every 2.5 seconds um i thought maybe i   could get away with every five seconds but i'm  getting trails still i'm getting much rounder   stars by moving it 15 degrees every two and a half  seconds rather than 30 degrees every five seconds   so it's not too bad it's just a little bit  tough on my neck to keep looking down at it   but i can adjust the tripod height to sort of  fix that i'm just using the stopwatch on my   phone to to watch the seconds go by and i've just  done some short tests so far but let's go ahead   and take a full two minute exposure now that i  think i have it working and we'll see what we get wow will you look at that i'm amazed at how good  this looks this is just again a single two minute   exposure with this barn door tracker let me zoom  in on it so you can see what i'm seeing here   just really good detail stars are nice and sharp  and round i think this is going to be a keeper i'm   going to try to take as many as i can before  sunrise here so i'm going to get right back   into it so i've taken 10 two-minute exposures  they're all looking good but i'm getting close   to the bottom of the bolt so i'm going to go  ahead and rewind it by turning it clockwise now   this way okay i'm done rewinding it i'm not  going to have to re-point the camera on my object   because uh by rewinding it i probably  threw off the pointing a little bit   and then i'll take 10 more two-minute  exposures uh and probably by then the sun   will be rising and off to stop so we'll have  20 two-minute exposures for 40 minutes total   well it's the next day i've gone ahead  and processed what i shot last night and   i gotta say i'm pretty impressed by this barn door  tracker i wasn't so sure if a manual tracker was   gonna be able to keep up with a modern dslr with  small pixels but as long as you rotate the bolt   frequently enough to avoid trailing i found it  works really well that took a little trial and   error of course the big advantage of using this  tracker over just shooting on a fixed tripod   is to get 40 minutes total time on my target like  i did last night i only had to shoot 20 photos at   2 minutes each if i was shooting without a tracker  to get to 40 minutes i would have had to do 600   photos at four seconds each so taking hundreds of  photos will wear out your camera's shutter faster   and take a lot longer to stack on your computer of  course there are some cons to this tracker too the   manual nature of it made it a bit uncomfortable  on my neck to be looking down at it for 40 minutes   just slowly moving that wheel and i suppose some  people would also find it pretty boring to just   manually track that long so keep those things in  mind what's next for this project well i want to   buy a used finder device like i mentioned with  maybe a crosshair eyepiece so i can better polar   align and that will allow me to try longer  focal lengths because i've only really tried   it seriously at 24 millimeters i did try a little  bit longer focal lengths but i wasn't getting good   results i think it was because of polar alignment  error so once i've done like a version two of this   i also want to test it against some of the cheaper  commercial options um like this omegon um lx2   windup tracker and the moveshoot move which is  a little bit motorized tracker but it's very   small and so you can look forward to a part two  eventually where i will show you my improvements   and try it against uh these options uh you know  30 tracker versus a little bit more expensive ones well the only thing left now is the image reveal  so let's start with the single unprocessed two   minute exposure here it is cropped in a  bit to fill the screen and we can zoom   in on some stars here just to show you that  they are indeed round okay and here is after   and all i did in the processing was really uh you  know stack with i think i did 12 darks i didn't   have time to do flats or bias so it's  just uh 20 20 lights and 12 darks matched   temperature darks and i i just stacked those  in deep sky stacker brought this into photoshop   and did my usual sort of playing around with  curves and saturation and stuff i also just   want to mention here again at the end that i  have a patreon and another perk of my patreon   is i now have an exclusive video just for people  who support me on patreon and that the topic   of that video is choosing different types of  deep sky objects and what kind of gear filters   and sky conditions you might need for different  types like if you want to shoot a star cluster   do you need a filter do you need a dark sky that  kind of thing if you want to shoot a constellation   what's the best focal length for that so i  go through some different types of deep sky   objects so if you're interested check out my  Patreon it starts at just one dollar a month   until next time this has been Nico  Carver from nebulaphotos.com Clear Skies

Channel: Nebula Photos

Views: 158,183

Keywords: astrophotography, astronomy, canon astrophotography, dslr astrophotography, dslr astrophotography for beginners, stars, star photography, night sky photography, nebula photos, nico carver, nico carver astrophotography, nico nebula photos, barn door tracker, milky way photography, how to photograph the milky way, scotch mount, how to make a barn door tracker, george haig, haig mount, rho ophiuchi, blue horsehead, budget astrophotography, canon t7, rokinon 24mm

Id: P_qqLA0WKJg

Length: 22min 28sec (1348 seconds)

Published: Thu Mar 25 2021